/*******************************************************************************
 * Copyright (c) 2000, 2013 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.internal.ui.text.java;

import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.OperationCanceledException;
import org.eclipse.jdt.core.CompletionProposal;
import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.JavaModelException;
import org.eclipse.jdt.internal.ui.JavaPlugin;
import org.eclipse.jdt.internal.ui.text.JavaHeuristicScanner;
import org.eclipse.jdt.internal.ui.text.Symbols;
import org.eclipse.jdt.ui.text.java.CompletionProposalCollector;
import org.eclipse.jdt.ui.text.java.ContentAssistInvocationContext;
import org.eclipse.jdt.ui.text.java.IJavaCompletionProposalComputer;
import org.eclipse.jdt.ui.text.java.JavaContentAssistInvocationContext;
import org.eclipse.jface.text.IDocument;
import org.eclipse.che.jface.text.ITextViewer;
import org.eclipse.che.jface.text.contentassist.ICompletionProposal;
import org.eclipse.che.jface.text.contentassist.IContextInformation;
import org.eclipse.che.jface.text.contentassist.IContextInformationExtension;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Point;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

/**
 * Computes Java completion proposals and context infos.
 *
 * @since 3.2
 */
public class JavaCompletionProposalComputer implements IJavaCompletionProposalComputer {

	private static final class ContextInformationWrapper implements IContextInformation, IContextInformationExtension {

		private final IContextInformation fContextInformation;
		private int fPosition;

		public ContextInformationWrapper(IContextInformation contextInformation) {
			fContextInformation= contextInformation;
		}

		/*
		 * @see IContextInformation#getContextDisplayString()
		 */
		public String getContextDisplayString() {
			return fContextInformation.getContextDisplayString();
		}

			/*
		 * @see IContextInformation#getImage()
		 */
		public Image getImage() {
			return fContextInformation.getImage();
		}

		/*
		 * @see IContextInformation#getInformationDisplayString()
		 */
		public String getInformationDisplayString() {
			return fContextInformation.getInformationDisplayString();
		}

		/*
		 * @see IContextInformationExtension#getContextInformationPosition()
		 */
		public int getContextInformationPosition() {
			return fPosition;
		}

		public void setContextInformationPosition(int position) {
			fPosition= position;
		}

		/*
		 * @see org.eclipse.jface.text.contentassist.IContextInformation#equals(java.lang.Object)
		 */
		@Override
		public boolean equals(Object object) {
			if (object instanceof ContextInformationWrapper)
				return fContextInformation.equals(((ContextInformationWrapper) object).fContextInformation);
			else
				return fContextInformation.equals(object);
		}

		/*
		 * @see java.lang.Object#hashCode()
		 * @since 3.5
		 */
		@Override
		public int hashCode() {
			return fContextInformation.hashCode();
		}
	}

    private static final long JAVA_CODE_ASSIST_TIMEOUT = Long.getLong("org.eclipse.jdt.ui.codeAssistTimeout", 5000).longValue();
            // ms //$NON-NLS-1$

    private String fErrorMessage;

    private final IProgressMonitor fTimeoutProgressMonitor;

    public JavaCompletionProposalComputer() {
        fTimeoutProgressMonitor = createTimeoutProgressMonitor(JAVA_CODE_ASSIST_TIMEOUT);
    }

    protected int guessContextInformationPosition(ContentAssistInvocationContext context) {
        return context.getInvocationOffset();
    }

    protected final int guessMethodContextInformationPosition(ContentAssistInvocationContext context) {
        final int contextPosition = context.getInvocationOffset();

        IDocument document = context.getDocument();
        JavaHeuristicScanner scanner = new JavaHeuristicScanner(document);
        int bound = Math.max(-1, contextPosition - 2000);

        // try the innermost scope of parentheses that looks like a method call
        int pos = contextPosition - 1;
        do {
            int paren = scanner.findOpeningPeer(pos, bound, '(', ')');
            if (paren == JavaHeuristicScanner.NOT_FOUND)
                break;
            int token = scanner.previousToken(paren - 1, bound);
            // next token must be a method name (identifier) or the closing angle of a
            // constructor call of a parameterized type.
            if (token == Symbols.TokenIDENT || token == Symbols.TokenGREATERTHAN)
                return paren + 1;
            pos = paren - 1;
        } while (true);

        return contextPosition;
    }

    private List<IContextInformation> addContextInformations(JavaContentAssistInvocationContext context, int offset) {
        List<ICompletionProposal> proposals = internalComputeCompletionProposals(offset, context);
        List<IContextInformation> result = new ArrayList<IContextInformation>(proposals.size());
        List<IContextInformation> anonymousResult = new ArrayList<IContextInformation>(proposals.size());

        for (Iterator<ICompletionProposal> it = proposals.iterator(); it.hasNext(); ) {
            ICompletionProposal proposal = it.next();
            IContextInformation contextInformation = proposal.getContextInformation();
            if (contextInformation != null) {
                ContextInformationWrapper wrapper = new ContextInformationWrapper(contextInformation);
                wrapper.setContextInformationPosition(offset);
                if (proposal instanceof AnonymousTypeCompletionProposal)
                    anonymousResult.add(wrapper);
                else
                    result.add(wrapper);
            }
        }

        if (result.size() == 0)
            return anonymousResult;
        return result;

    }

    /*
     * @see org.eclipse.jface.text.contentassist.ICompletionProposalComputer#computeContextInformation(org.eclipse.jface.text
     * .contentassist.TextContentAssistInvocationContext, org.eclipse.core.runtime.IProgressMonitor)
     */
    public List<IContextInformation> computeContextInformation(ContentAssistInvocationContext context, IProgressMonitor monitor) {
        if (context instanceof JavaContentAssistInvocationContext) {
            JavaContentAssistInvocationContext javaContext = (JavaContentAssistInvocationContext)context;

            int contextInformationPosition = guessContextInformationPosition(javaContext);
            List<IContextInformation> result = addContextInformations(javaContext, contextInformationPosition);
            return result;
        }
        return Collections.emptyList();
    }

    /*
     * @see org.eclipse.jface.text.contentassist.ICompletionProposalComputer#computeCompletionProposals(org.eclipse.jface.text
     * .contentassist.TextContentAssistInvocationContext, org.eclipse.core.runtime.IProgressMonitor)
     */
    public List<ICompletionProposal> computeCompletionProposals(ContentAssistInvocationContext context, IProgressMonitor monitor) {
        if (context instanceof JavaContentAssistInvocationContext) {
            JavaContentAssistInvocationContext javaContext = (JavaContentAssistInvocationContext)context;
            return internalComputeCompletionProposals(context.getInvocationOffset(), javaContext);
        }
        return Collections.emptyList();
    }

    private List<ICompletionProposal> internalComputeCompletionProposals(int offset, JavaContentAssistInvocationContext context) {
        ICompilationUnit unit = context.getCompilationUnit();
        if (unit == null)
            return Collections.emptyList();

        ITextViewer viewer = context.getViewer();

		CompletionProposalCollector collector= createCollector(context);
		collector.setInvocationContext(context);

		// Allow completions for unresolved types - since 3.3
		collector.setAllowsRequiredProposals(CompletionProposal.FIELD_REF, CompletionProposal.TYPE_REF, true);
		collector.setAllowsRequiredProposals(CompletionProposal.FIELD_REF, CompletionProposal.TYPE_IMPORT, true);
		collector.setAllowsRequiredProposals(CompletionProposal.FIELD_REF, CompletionProposal.FIELD_IMPORT, true);

		collector.setAllowsRequiredProposals(CompletionProposal.METHOD_REF, CompletionProposal.TYPE_REF, true);
		collector.setAllowsRequiredProposals(CompletionProposal.METHOD_REF, CompletionProposal.TYPE_IMPORT, true);
		collector.setAllowsRequiredProposals(CompletionProposal.METHOD_REF, CompletionProposal.METHOD_IMPORT, true);

		collector.setAllowsRequiredProposals(CompletionProposal.CONSTRUCTOR_INVOCATION, CompletionProposal.TYPE_REF, true);

		collector.setAllowsRequiredProposals(CompletionProposal.ANONYMOUS_CLASS_CONSTRUCTOR_INVOCATION, CompletionProposal.TYPE_REF, true);
		collector.setAllowsRequiredProposals(CompletionProposal.ANONYMOUS_CLASS_DECLARATION, CompletionProposal.TYPE_REF, true);

		collector.setAllowsRequiredProposals(CompletionProposal.TYPE_REF, CompletionProposal.TYPE_REF, true);

		// Set the favorite list to propose static members - since 3.3
		collector.setFavoriteReferences(getFavoriteStaticMembers());

		try {
			Point selection= viewer.getSelectedRange();
			if (selection.y > 0)
				collector.setReplacementLength(selection.y);
			unit.codeComplete(offset, collector, fTimeoutProgressMonitor);
		} catch (OperationCanceledException x) {
//			IBindingService bindingSvc= (IBindingService)PlatformUI.getWorkbench().getAdapter(IBindingService.class);
//			String keyBinding= bindingSvc.getBestActiveBindingFormattedFor(IWorkbenchCommandConstants.EDIT_CONTENT_ASSIST);
//			fErrorMessage= Messages.format(JavaTextMessages.CompletionProcessor_error_javaCompletion_took_too_long_message, keyBinding);
			JavaPlugin.log(x);
		} catch (JavaModelException x) {
//			Shell shell= viewer.getTextWidget().getShell();
//			if (x.isDoesNotExist() && !unit.getJavaProject().isOnClasspath(unit))
//				MessageDialog.openInformation(shell, JavaTextMessages.CompletionProcessor_error_notOnBuildPath_title, JavaTextMessages.CompletionProcessor_error_notOnBuildPath_message);
//			else
//				ErrorDialog.openError(shell, JavaTextMessages.CompletionProcessor_error_accessing_title, JavaTextMessages.CompletionProcessor_error_accessing_message, x.getStatus());
			JavaPlugin.log(x);
		}

		ICompletionProposal[] javaProposals= collector.getJavaCompletionProposals();
		int contextInformationOffset= guessMethodContextInformationPosition(context);
		if (contextInformationOffset != offset) {
			for (int i= 0; i < javaProposals.length; i++) {
				if (javaProposals[i] instanceof JavaMethodCompletionProposal) {
					JavaMethodCompletionProposal jmcp= (JavaMethodCompletionProposal) javaProposals[i];
					jmcp.setContextInformationPosition(contextInformationOffset);
				}
			}
		}

		List<ICompletionProposal> proposals= new ArrayList<ICompletionProposal>(Arrays.asList(javaProposals));
		if (proposals.size() == 0) {
			String error= collector.getErrorMessage();
			if (error.length() > 0)
				fErrorMessage= error;
		}
		return proposals;
	}

	/**
	 * Returns a new progress monitor that get cancelled after the given timeout.
	 * 
	 * @param timeout the timeout in ms
	 * @return the progress monitor
	 * @since 3.5
	 */
	private IProgressMonitor createTimeoutProgressMonitor(final long timeout) {
		return new IProgressMonitor() {

			private long fEndTime;
			
			public void beginTask(String name, int totalWork) {
				fEndTime= System.currentTimeMillis() + timeout;
			}
			public boolean isCanceled() {
				return fEndTime <= System.currentTimeMillis();
			}
			public void done() {
			}
			public void internalWorked(double work) {
			}
			public void setCanceled(boolean value) {
			}
			public void setTaskName(String name) {
			}
			public void subTask(String name) {
			}
			public void worked(int work) {
			}
		};
	}

	/**
	 * Returns the array with favorite static members.
	 * 
	 * @return the <code>String</code> array with with favorite static members
	 * @see org.eclipse.jdt.core.CompletionRequestor#setFavoriteReferences(String[])
	 * @since 3.3
	 */
	private String[] getFavoriteStaticMembers() {
		//todo
//		String serializedFavorites= PreferenceConstants.getPreferenceStore().getString(PreferenceConstants.CODEASSIST_FAVORITE_STATIC_MEMBERS);
//		if (serializedFavorites != null && serializedFavorites.length() > 0)
//			return serializedFavorites.split(";"); //$NON-NLS-1$

		return new String[0];
	}

	/**
	 * Creates the collector used to get proposals from core.
	 *
	 * @param context the context
	 * @return the collector
	 */
	protected CompletionProposalCollector createCollector(JavaContentAssistInvocationContext context) {
//		if (PreferenceConstants.getPreferenceStore().getBoolean(PreferenceConstants.CODEASSIST_FILL_ARGUMENT_NAMES))
			return new FillArgumentNamesCompletionProposalCollector(context);
//		else
//			return new CompletionProposalCollector(context.getCompilationUnit(), true);
	}

	/*
	 * @see org.eclipse.jface.text.contentassist.ICompletionProposalComputer#getErrorMessage()
	 */
	public String getErrorMessage() {
		return fErrorMessage;
	}

	/*
	 * @see org.eclipse.jdt.ui.text.java.IJavaCompletionProposalComputer#sessionStarted()
	 */
	public void sessionStarted() {
	}

	/*
	 * @see org.eclipse.jdt.ui.text.java.IJavaCompletionProposalComputer#sessionEnded()
	 */
	public void sessionEnded() {
		fErrorMessage= null;
	}
}
